1. Field of the Invention
The present invention relates generally to a vehicle securing system to prevent the vehicle from rolling away after turning off the ignition, and more specifically to a vehicle securing system for a vehicle having an automated transmission.
2. Description of the Related Art
Transmissions for motor vehicles are known in various embodiments. One such transmission is primarily a manually-shifted transmission, which in a vehicle having such a transmission is shifted manually by the driver with the help of a gearshift lever. The gear changing process is composed of the selection process to reach the shift pathway of the gear stage that is to be engaged, and the actual engagement process of the new gear stage.
In addition to such manually-shifted transmissions, automated transmissions are also known in which the selection process and the subsequent shifting process of the gear stages takes place through actuators coupled with the transmission. In one such automated transmission the selection and shifting process is carried out, for example, through programmed controls by actuators that are coupled to a force transfer section having internal transmission shift elements, such as, for example, a central selector shaft and sliding selector rods.
The known automated transmissions exhibit the following problem: there exists no vehicle securing system such as is the case with a stepped mechanism. After turning off the motor vehicle, however, the selector lever position can also be changed on the automated transmission, and it can be moved from N to D, for example. However, because the control device of the automated transmission cannot remain active indefinitely, and signals from additional control devices can no longer be evaluated after the ignition is xe2x80x9coff,xe2x80x9d no activation occurs in the automated transmission when moving the selector lever as described above.
The result is that when the ignition is turned off and the selector lever is moved from N to D the drive train remains open, although the driver expects a gear to be engaged and the vehicle to be prevented from rolling away.
Accordingly, it is an object of the present invention to provide a vehicle securing system for a motor vehicle having an automated transmission, to prevent the vehicle from rolling away.
In accordance with one aspect of the present invention there is provided a vehicle securing system, which is provided particularly for vehicles having an automated transmission. The system includes a transmission with a plurality of gear stages, and at least one control device that receives a plurality of the vehicle""s operating parameters and processes them, as well as controls the transmission in such a way that a selected gear is engaged. The control device causes a gear to be engaged as a function of at least one operating parameter when the vehicle moves at a speed that is lower than a certain limit value, and in the event that the driver selects one of the gear stages after having switched off the ignition of the vehicle.
In accordance with another aspect of the present invention a method for preventing rolling of a vehicle having an automated transmission is provided.
The advantage of this vehicle securing system is that even after the ignition has been switched off, a defined condition of the transmission is provided that is easily executable by the driver.
It is particularly advantageous if, after switching off the ignition, a subsequent operation period for at least a certain period of time follows for at least one control device (the selector lever, the ABS, etc.) and for the transmission so that the driver can perform a gear change. That period of time will always be available to the driver and will be established in such a way that it will be possible under normal conditions to engage the vehicle securing system after switching off the vehicle.
In order to provide the driver with feedback about the state of the control devices, or in the present case about the engagement of the vehicle securing system, the engagement of the gear stage is indicated acoustically and/or visually.
Tests have shown that the duration of the subsequent operation period should preferably be about 10 seconds. That period of time is sufficiently long to activate the vehicle securing system.
Alternatively, the vehicle securing system can also be engaged as a function of other and/or additional vehicle operating parameters. The time interval does not have to be a predetermined duration, but the subsequent operation period can also be initiated, for example, by the operation of a brake pedal. As long as the driver presses down on the brake pedal after the ignition has been switched xe2x80x9coff,xe2x80x9d the parking stage (one of the gear stages) can be engaged.
In order to provide a vehicle securing system in accordance with the present invention with the help of the power train, a clutch must be engaged after engaging the gear stage.
Most motor vehicles offered today have an ignition lock, so that switching off of the ignition occurs by means of the ignition lock. The position of the ignition lock is accordingly transmitted to the control device as an operating parameter.
A further operating parameter is provided by the actuation of the brake pedal. The time interval for the subsequent operation of the control device etc. can, as already mentioned above, be provided by a predetermined time interval and/or additionally by the actuation of the brake pedal.
In order to recognize the presence of a driver, operation of the vehicle securing system can, alternatively, be enabled by the actuation of an accelerator pedal. In that context, it should be mentioned that each operating parameter that is suitable for recognizing the presence of a driver, and that is suitable for preventing unintended movement of the selector lever, can also be utilized for effecting the control of the vehicle securing system.
Preferably, the threshold value for the vehicle""s speed should be about zero km/h. It is only when the vehicle is stopped that a jerking movement can be prevented when engaging the vehicle securing system.
If the threshold value for the vehicle""s speed is a maximum of about 3 km/h, such a jerking movement is still acceptable.
The driver is informed acoustically and/or visually about the end of the subsequent operation period. Thereby the driver will be made aware that a movement of the selector lever after the end of the subsequent operation period will not lead to the desired action. For example, the driver can, however, request a xe2x80x9cwake-upxe2x80x9d function by again actuating the brake pedal, which then makes available a renewed subsequent operation period, to enable engagement of the vehicle securing system.
The foregoing task, along with the features and the advantages of the present invention, can be better understood when considering the following detailed description of the preferred embodiments of the present invention, together with the accompanying drawing, in which several vehicle components are shown in a diagrammatic form, for explaining the vehicle securing system.